Three-Layer Cord, Rubberized In Situ, For A Tire Carcass Reinforcement

Abstract

Metal cord (C- 1 ) with three layers (C 1 , C 2 , C 3 ), which is rubberized in situ, comprising a core or first layer ( 10 , C 1 ) of diameter d 1 , around which there are wound together in a helix at a pitch p 2 , in a second layer (C 2 ), N wires ( 11 ) of diameter d 2 , N varying from 5 to 7, around which there are wound together in a helix at a pitch p 3 , in a third layer (C 3 ), P wires ( 12 ) of diameter d 3 , the said cord being characterized in that it has the following characteristics (d 1 , d 2 , d 3 , p 2 and p 3 being expressed in mm): 0.08≦d 1 ≦0.40; 0.08≦d 2 ≦0.35; 0.08≦d 3 ≦0.35; 5π(d 1 +d 2 )<p 2 ≦p 3 <10π(d 1 +2d 2 +d 3 ); over any 2 cm length of cord, a rubber composition called “filling rubber” ( 13 ) is present in each of the capillaries ( 14 ) lying on the one hand between the core (C 1 ) and the N wires of the second layer (C 2 ), and on the other hand between the N wires of the second layer (C 2 ) and the P wires of the third layer (C 3 ); the content of filling rubber in the cord is comprised between 5 and 30 mg per gram of cord.

1 . A metal cord with three layers, which is rubberized in situ, comprising a core or first layer of diameter d 1 , around which there are wound together in a helix at a pitch p 2 , in a second layer, N wires of diameter d 2 , N varying from 5 to 7, around which there are wound together in a helix at a pitch p 3 , in a third layer, P wires of diameter d 3 , wherein the said cord has the following characteristics (d 1 , d 2 , d 3 , p 2  and p 3  being expressed in mm):
 0.08≦d 1 ≦0.40;   0.08≦d 2 ≦0.35;   0.08≦d 3 ≦0.35;   5π(d 1 +d 2 )<p 2 ≦p 3 <10π(d 1 +2d 2 +d 3 );   over any 2 cm length of cord, a rubber composition called “filling rubber” is present in each of the capillaries lying on the one hand between the core and the N wires of the second layer, and on the other hand between the N wires of the second layer and the P wires of the third layer;   the content of filling rubber in the cord is comprised between 5 and 30 mg per gram of cord.   
     
     
         2 . The cord according to  claim 1 , wherein the rubber of the filling rubber is a diene elastomer. 
     
     
         3 . The cord according to  claim 2 , wherein the diene elastomer is chosen from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, copolymers of butadiene, copolymers of isoprene, and blends of these elastomers. 
     
     
         4 . The cord according to  claim 3 , wherein the diene elastomer is an isoprene elastomer. 
     
     
         5 . The cord according to  claim 1 , wherein the following characteristics are satisfied (with d 1 , d 2 , d 3  being in mm):
 0.10≦d 1 ≦0.35;   0.10≦d 2 ≦0.30;   0.10≦d 3 ≦0.30.   
     
     
         6 . The cord according to  claim 1 , wherein the following characteristics are satisfied:
 for N=5: 0.6<(d 1 /d 2 )<0.9;   for N=6: 0.9<(d 1 /d 2 )<1.3;   for N=7: 1.3<(d 1 /d 2 )<1.6.   
     
     
         7 . The cord according to  claim 1 , wherein the N and P wires of the second and third layers are wound in the same direction of twisting. 
     
     
         8 . The cord according to  claim 1 , wherein p 2  and p 3  are comprised in a range from 5 to 30 mm. 
     
     
         9 . The cord according to  claim 1 , wherein d 2 =d 3 . 
     
     
         10 . The cord according to  claim 1 , wherein p 2 =p 3 . 
     
     
         11 . The cord according to  claim 1 , wherein the third layer comprises 10 to 14 wires. 
     
     
         12 . The cord according to  claim 1 , wherein the third layer is a saturated layer. 
     
     
         13 . The cord according to  claim 1 , wherein the core consists of a single wire. 
     
     
         14 . The cord according to  claim 13 , of 1+6+11 or 1+6+12 construction. 
     
     
         15 . The cord according to  claim 1 , wherein the content of filling rubber is comprised between 5 and 25 mg per g of cord. 
     
     
         16 . The cord according to  claim 1 , wherein, in an air permeability test, it has an average air flow rate of less than 2 cm 3 /min. 
     
     
         17 . The cord according to  claim 16 , wherein, in the air permeability test, it has an air flow rate less than or at the most equal to 0.2 cm 3 /min. 
     
     
         18 . A multi-strand rope at least one of the strands of which is a cord according to  claim 1 . 
     
     
         19 .- 20 . (canceled) 
     
     
         21 . A tire comprising a cord according to  claim 1 . 
     
     
         22 . The tire according to  claim 21 , said tire being a tire of an industrial vehicle. 
     
     
         23 . The tire according to  claim 21 , the cord being present in the carcass reinforcement of the tire.